I want to save/read an object to disk in c#. some of it's properties are not marked with [Serializable].
Is there any other way to save it?
I don't care about the format of the object on the disk, I only want to dump it to the disk and read it.
Any suggestions?
An alternative to the suggested XmlSerializer would be protobuf-net. It's a .net implementation of Google's protobuf written by a SO/StackExchange own Marc Gravell.
Note, you will have to have access to the objects since protobuf-net supports only custom classes that:
are marked as data-contract
have a parameterless constructor
for Silverlight: are public
If that doesn't work for you, you could either write your own solution or, depending on your scope, use an object db like eloquera.
The XmlSerializer class does not require an object to be marked as serializable, but it only saves the public fields and properties. If you need to serialize the private members, you are out of luck unless you write your own serializer.
Related
I have some data that is persisted in a database. The serialized content was originally written using the default NetDataContractSerializer with a DataContract attribute on the classes.
Now I want to move to using classes that implement IXmlSerializable to have more control over the serialized content and make it leaner and faster.
How will I be able to read the current content as well as store future content in the new way.
I have looked into ISurrogateSelector, but it doesn't seem to do the trick as the ISerializationSurrogate interface only supports getting and setting object data as the ISerializable interface, but no way to specify ReadXml and WriteXml as in IXmlSerializable interface. As I am reading in the stream, I don't have any information about the format other than the stream itself.
The deserialization must produce the same class instance regardless of the original serialization method.
I need to make a solution that uses .NET Framework 4.6
On my own object I can add the metatag [Serializable] to make it serializable. Now I use a 3rd party library that I need to be serializable. I inspected the code and it should not be a problem. Is there a way to fix this without altering the 3rd party code?
My advice would be: serialize data, not implementation. The fact of the existence of a 3rd-party object is nothing to do with the data; that is an implementation detail. As such, I always offer the same advice: if serialization ever gets complex, the first thing to do is to introduce a separate DTO model that represents the data in isolation of the implementation, and just map the current state to that DTO. This allows you to handle implementation changes without impact on the storage, and allows otherwise non-serializable objects to be serialized.
Some serializers offer workarounds - for example with protobuf-net you can a: supply the serialization information for any type at runtime, and b: supply a "surrogate" to use automatically when it gets tricky, but - using a DTO model is simpler and easier to maintain.
Your use of [Serializable] suggests BinaryFormatter; in my opinion, this is almost never a good choice for any kind of storage, since BinaryFormatter relies on implementation details. It works nicely for passing data between two in-sync app-domains, though
If the types are public you should be able to use the XmlSerializer to do what you want.
There's more information on this here
Serializes and deserializes objects into and from XML documents. The
XmlSerializer enables you to control how objects are encoded into XML.
Exactly take your subclass and make it serializable.
[Serializable] public class Foo: Bar {}
Write an adapter or be prepared to do something more extreme like disassembling the assembly, injecting the serializable attribute and reassembling.
Based on my understanding, SerializableAttribute provides no compile time checks, as it's all done at runtime. If that's the case, then why is it required for classes to be marked as serializable?
Couldn't the serializer just try to serialize an object and then fail? Isn't that what it does right now? When something is marked, it tries and fails. Wouldn't it be better if you had to mark things as unserializable rather than serializable? That way you wouldn't have the problem of libraries not marking things as serializable?
As I understand it, the idea behind the SerializableAttribute is to create an opt-in system for binary serialization.
Keep in mind that, unlike XML serialization, which uses public properties, binary serialization grabs all the private fields by default.
Not only this could include operating system structures and private data that is not supposed to be exposed, but deserializing it could result in corrupt state that can crash an application (silly example: a handle for a file open in a different computer).
This is only a requirement for BinaryFormatter (and the SOAP equivalent, but nobody uses that). Diego is right; there are good reasons for this in terms of what it does, but it is far from the only option - indeed, personally I only recommend BinaryFormatter for talking between AppDomains - it is not (IMO) a good way to persist data (to disk, in cache, to a database BLOB, etc).
If this behaviour causes you trouble, consider using any of the alternatives:
XmlSerializer, which works on public members (not just the fields), but demands a public parameterless constructor and public type
DataContractSerializer, which can work fully opt-in (using [DataContract]/[DataMember]), but which can also (in 3.5 and above) work against the fields instead
Also - for a 3rd-party option (me being the 3rd party); protobuf-net may have options here; "v2" (not fully released yet, but available as source) allows the model (which members to serialize, etc) to be described independently of the type, so that it can be applied to types that you don't control. And unlike BinaryFormatter the output is version-tolerant, known public format, etc.
I would like to know the most common scenarios where xml serialization may fail in .NET.
I'm thinking mainly of XmlSerializer here:
it is limited to tree-like data; it can't handle full object graphs
it is limited to public members, on public classes
it can't really do much with object members
it has some weaknesses around generics
like many serializers, it won't touch instance properties on a collection (bad practice in the first place)
xml simply isn't always a good choice for large data (not least, for performance)
requires a public parameterless constructor
DataContractSerializer solves some of these, but has its own limitations:
it can't handle values in attributes
requires .NET 3.0 (so not much use in 2.0)
Cannot easily serialize generic collections.
See another question: C# XML Serialization Gotchas
Depending on the serializer, cyclic references may not work
Using the shadows keyword has also broken serialization and deserialization for me because the shadowing causes a new implementation of that property to exist making it incompatible for proper reconstruction. Only use overloads if you want to retype to the specific for a subclass.
TimeSpan objects are not serializable. IDictionary-implementing types are not serializable either (although they can be serialized with some manual massaging).
AFAIK, classes marked as [Obsolete] are not serialized by XmlSerializer since .NET 2.0
I've got a program that picks up some code from script files and compiles it.
And It works fine.
The problem is: in the scripts I declare a couple of classes and I want to serialize them.
Obviously the C# serializer (xml and binary) doesn't like to serialize and the de-serialize object defined in a in-memory assembly.
I prefer to don't leave the in-memory assembly so i'm looking for another way of serializing, but in case, is possible to build assembly in memory and eventually write it on file ?
You could always write your own ToXml function using reflection to write out your property data to a string. Then your object would deserialize itself.
Just a thought.
If you want to create assemblies dynamically look into IL emitting via reflection. Here is a good article to get you started.
So just to clarify, are you asking how you can serialize a type if it hasn't got the [Serializable] attribute applied?
One solution is to use the WCF Data Contract Serializer: http://msdn.microsoft.com/en-us/library/ms731923.aspx.
Obviously this will only work if you can target .Net 3.0 or higher.
Alternately you can implement an ISerializationSurrogate. Jeffrey Richter has a great introduction at http://msdn.microsoft.com/en-us/magazine/cc188950.aspx.
I would avoid all built-in serialization whenever possible, both are badly broken. For example, XML serialization doesn't support dictionaries and normal serialization/SOAP doesn't support generics. And both have versioning issues.
It is time consuming, but createing ToXML and FromXML methods is probably to most effective way to go.
Hava a look at here for custom serialisers, which is a sample for dictionary XML serializing
I'm slightly confused by the statement that the XmlSerializer can't serialize dynamically generated types. The XmlSerializer generates it's own serialization code dynamically as well during construction so there should be no issue with it serializing your type.
You may need to decorate your dynamic classes with the appropriate attributes, depending on what you are generating (like derived classes), but there shouldn't be any issue with using the XmlSerializer in the situation you described.
If you could post details about the issues the XmlSerializer is giving you I can help you work out what the problem is.
Also, I'm of the belief that auto-generating code is in general a blessing. All to often have I had to go back into a class to fix one or all of the copy/paste/save/load functions, just because someone forgot to update them when adding a new variable. Save/Load code is boiler plate code. Let the computers write it.